45cm=4.5__dm
5000nm=5000*10(-7)__cm=5*10(-4次方) nm为纳米
400km=400*10000__dm =4*10(6次方)
15m/s=_54_km/h=_0.9_km/min
1m/s=3.6__km/h=_100_cm/s
45cm=4.5__dm
5000nm=5000*10(-7)__cm=5*10(-4次方) nm为纳米
400km=400*10000__dm =4*10(6次方)
15m/s=_54_km/h=_0.9_km/min
1m/s=3.6__km/h=_100_cm/s